As a little workout for my newly acquired CGI muscles I put together:

use strict;
use warnings;
use CGI::Pretty;

my %data;

while (<DATA>) {
    chomp;
    
    my ($code, $date, $time) = split /\s+/;
    
    next if ! defined $time;
    
    push @{$data{$date}}, [$code, $time];
}

my $cgi = CGI->new();
my $tableContents;

for (sort keys %data) {
    $tableContents .= $cgi->Tr ($cgi->td ('&nbsp;'));
    $tableContents .= $cgi->Tr ($cgi->td ($_));
    
    for (sort {$a->[1] cmp $b->[1]} @{$data{$_}}) {
        $tableContents .= $cgi->Tr (
                $cgi->td ($_->[0]), $cgi->td ($_->[1])
            ); 
    };
}

#print $cgi->header ();
print $cgi->start_html ();
print $cgi->table ($tableContents);
print $cgi->end_html ();

__DATA__
CA642997     2007-01-29     03:05:00
CA651167     2007-01-29     03:05:00
CA651038     2007-01-29     19:00:00
CA650995     2007-01-30     19:00:00
CA652568     2007-01-31     01:05:00
CA652880     2007-01-31     01:30:00
CA652884     2007-01-31     06:00:00
CA643602     2007-02-01     00:30:00
CA652881     2007-02-01     01:00:00
[download]

which prints output that renders as (having stripped off headers and stuff for posting here):